Engineering lotus-surface-mimicking organic/inorganic (g-C₃N₄/FeOOH) heterojunction photocatalysts for excellent dual-channel ·OH generation

This study successfully constructed a g-C₃N₄/FeOOH S-scheme heterojunction photocatalyst with lotus-leaf structural effects, addressing the challenges of insufficient oxygen and water adsorption sites and high photocurrent recombination rates in g-C₃N₄ photocatalysts. The optimized photocatalyst exhibits outstanding performance, generating hydroxyl radicals via dual pathways under visible light (generation rate: 2.8 μmol/(L·min)). The lotus-leaf effect in the composite was confirmed through morphology analysis, static water contact angle measurements, and oxygen adsorption/desorption experiments, demonstrating an 18.9-fold enhancement in oxygen capacity. In situ XPS, built-in electric field intensity measurements, and theoretical calculations confirm that the built-in electric field at the interface, directed from g-C₃N₄ toward FeOOH, drives an S-scheme charge transport pathway. This not only achieves efficient spatial separation of photogenerated carriers but also uniquely preserves the system's strongest redox capability, significantly enhancing photocatalytic efficiency. Furthermore, in situ infrared spectroscopy and electron paramagnetic resonance studies confirm the composite material's dual-channel mechanism for hydroxyl radical generation via oxygen reduction and water oxidation. This work provides robust experimental and theoretical foundations for understanding and designing S-scheme heterojunctions for dual-channel hydroxyl radical generation in photocatalysis.